Dear mam, I'm assuming it is a concrete structure.

I would look for the material constituents that is used for the building. Other factors might also be the aggregates that were used in the preparing the concrete. Siliceous aggregates tend to have more thermal stability than the calcareous ones. i.e. you might also check for the decomposition range of materials and their thermal stability.

Thanks for your answer, do you have any idea about the stone structure?

Can i know the type of stone used?

sandstone 

I'm working on quartz sandstones. I find it thermally stable at elevated temperatures,

Reference: 

Article Effective utilisation of quartz sandstone mining wastes: A t...

Thank you, this reference confirms the thermal stability of the sandstone ..now the primary question is the findings of the big differences in the thermal stability among the rooms that have the same orientation and sandstone structure :(  

Thanks a lot